title: Studies on thermal adaptation in Tetrahymena membrane lipids. Modification of positional distribution of phospholipid acyl chains in plasma membranes, mitochondria and microsomes.
abstract: The positional distribution of fatty acyl chains in major glycerophospholipids (phosphatidylethanolamine, phosphatidylcholine and 2-aminoethylphosphonolipid) of three membrane fractions (plasma membranes, mitochondria and microsomes) of the thermotolerant Tetrahymena pyriformis NT-1 cells was analyzed at various time intervals within 10 h after a temperature shift from 39 to 15 degrees C. During this period of acclimation there were no changes in both the total phospholipid content and its proportional composition. At the 1-position, the content of palmitate in phosphatidylethanolamine (present solely in diacyl type), diacylphosphatidylcholine, and diacyl-(2-aminoethyl)phosphonolipid was decreased progressively after temperature-shift, while gamma-linolenate increased in a complementary fashion, in mitochondria and microsomes. The increase in the percentage of linoleate was compensated by the decrease in oleate at the 2-position of two 1,2-diacylphospholipids. On the other hand, as for 1-alkyl-2-acyl-phospholipids, a marked increment in gamma-linolenate occurred, with a decline of oleate and linoleate at the 2-position of 1-alkyl-2-acyl-phosphatidylcholine, but no significant alterations were seen at the 2-position of 1-alkyl-2-acyl-(2-aminoethyl)phosphonolipid. The results suggest that the newly modified phospholipid molecular species such as 1-gamma-linolenoyl-2-linoleoyl-phosphatidylethanolamine and 1-hexadecyl-2-gamma-linolenoyl-phosphatidylcholine disseminate rapidly to other cell compartments and that they would play a pivotal role in the adaptive amelioration of altered membrane physical states during the cold acclimation.
mesh_terms: D000818:Animals; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D013696:Temperature; D013769:Tetrahymena pyriformis / Q000502:physiology*
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010743:Phospholipids